A steady stance (standing position) is the cornerstone of your future success.

The stance

Be wear of how you stand on the shooting line. Your feet should be firmly on the ground, your body weight should be spread out evenly on your both feet and you should also control your feet alignment in relation to the target (target is called also as buttress or but).
      There are two basic stances; square stance and open stance, but I teach you here only the square stance, because it is easier to execute and repeat in this early stage. Take a convenient position on the line so that your feet are a bit spread apart from each other. You should also be standing 90 degrees to the target (archer A). Don't spread your feet to much (about 40 centimetres in between is ok), because it will tire your feet and especially your knees fast. 
      Stand straight and firmly.  Your feet should be parallel to each other and not like Chaplin kept his feet spread-eagled. Don't lock your knees back, let them be relaxed!
 
In archery, unlike many other shooting sports the archer must stand on the shooting line so that his feet are on both sides of the line. 

Check again your stance. How does it feel? Unsteady or not?  If not, you have learned the first important thing in archery - standing conveniently.
Lean now with your upper body a bit towards your toes, so that you are still able to fight the sudden wind blows but your heels are still touching the ground. Stand up straight as you can like the top of your head were reaching up for the skies. Balance now your elbows so that they both are on the same level. Like in the letter T. Relax both your neck and shoulders (don't try to hide your head between the shoulders by lifting them up) and keep the shoulders down all the time. Check that you are standing still in 90 degrees to the target and look your face turned straight to the ten ring! Make sure that your chin bone is horizontally lined. Before lifting the bow up take a couple deep breaths, so there is enough oxygen in your lungs and vessels for the next step.

Most of the archers stand in a slight angled standing position (about 45 degrees to target, like the archer B). It is called the open stance. This leaves the string a bit more space to pass your inner arm and helps you to get the draw more to your back muscles. You can try it too, but I recommend that you stick to the stance for time being. It is so much easier to perform and control. If you however try the open stance, make sure that you have the same angle between your shots and ends.